December 12, 2011

I’m just back from a three-day conference in Bonn, Germany, which I unhesitatingly nominate as the best I’ve ever been to. To begin with, the subject was a guaranteed winner: sauropod gigantism. I can hardly overstate how awesome it was to hear 43 talks about or relevant to sauropod gigantism (sixteen on the first day, fifteen on the second and twelve on the third). For another thing, it was one of those rare occasions where all three SV-POW!sketeers got together — I think the fourth or fifth time ever. For yet another, I met honorary SV-POW!er Ranger Vanessa Graff and Brontomerus artist Francisco “Paco” Gasco for the first time. And it’s always good to spend time with people like biomechanics wizard John Hutchinson and occasional SV-POW! guest-blogger Heinrich Mallison. (Apologies to those I’ve not mentioned by name: lots of good people!)

Left to right: Mike, Darren, Matt, Paco. Note the complete lack of commitment in Paco's MYDD expression. Matt's showing how it should be done. Darren seems to have had something unfortunate happen to his nose, and (in this picture, not in real life) look like a hobgoblin. Nothing personal. Just saying.

The meeting was The 2nd International Workshop on Sauropod Biology and Gigantism: a public meeting of DFG Research Unit 533 “Biology of the Sauropod Dinosaurs”. That’s a mostly German group, headed by Martin Sander, which has been working for nearly eight years on multiple lines towards understanding the evolution of gigantism. Along the way, that group has produced 105 publications and counting, including a very nice hardcover volume Biology of the Sauropod Dinosaurs: Understanding the Life of Giants, available for the reasonable price of £40 [amazon.co.uk] or $50 [amazon.com]. (Compare with the price of £95 [amazon.co.uk] or $190 [amazon.com] for the comparably sized Geological Society volume on the history of dinosaur palaeontology. Hang your head in shame, GeolSoc.) Maybe most importantly, the group published a big synthesis paper at Biological Reviews that is freely available, and which everyone interested in sauropod palaeobiology should read to understand the current state of the field. Although I certainly don’t agree with everything that’s been published by the group, overall it’s done excellent work and plenty of it. So it was a real privilege to be a part of this second public meeting. (Matt and I were also at the first, three years ago.)

Maybe the greatest thing about this meeting was the involvement of many scientists whose usual work is not on sauropods, but who were able to bring their expertise in other fields and apply it to sauropod-related problems. For example, Jurgen Hummel on on digestive energetics, Michael Fagan on biomechanical modelling, Tom Schanz on soil mechanism (and implications for interpreting tracks) and Jennifer McElwain on plant growth in simulated palaeoatmospheres. The word “interdisciplinarary” is bandied around a lot, but this conference really fulfilled that description. That’s truly helpful: for example, five minutes’ conversation with people who actually understand digestive energetics saved me weeks or months of what would have turned out to be fruitless work on the Nourishing Vomit Of Eucamerotus hypothesis.

Wedel is disappointed to discover that baby sauropods didn't need Nourishing Vomit; but Naish is delighted.

Another huge benefit of working with scientists who have other specialisations is the ability to triangulate on a problem. For example, in my talk on how little we truly know about sauropod necks, I mentioned that we don’t know whether their intervertebral joints were fibrocartilaginous, like those of mammals and crocs, or synovial, like those of birds. I had been hoping to get a student working on comparative dissections of birds and crocs in the hope of identifying osteological correlates that might allow us to recognise relevant indications in sauropod bones. But Martin Sander pointed out that histological analysis of the preserved osseous articular surfaces might allow us to tell directly what kind of joint was used — an approach that would never have occurred to me.

So: scientists who know about things other than sauropods. Recommended.

Unlike most conferences, this one allowed time for discussion after each talk — something that made a huge difference. The slots allocated were each 30 minutes long, but speakers were asked to use only half of that time. In practice, many talks ran twenty minutes or so, but nevertheless the kind of discussion that you get in ten minutes is qualitatively different from the rather perfunctory one-quick-question-and-move-on that you get at most meetings. It was in those intervals that a lot of important ambiguities were clarified, misunderstandings remedied, and ideas explored. (I’d love to see this become more widespread, but of course I understand the difficulty of fitting all the talks into the programme at a larger conference like SVPCA. Not to mention SVP.)

Unsurprisingly, highlight talks for me included those by Matt (reviewing the last three years’ developments in pneumaticity, and considering the way forward) and Darren (presenting our no-necks-for-sex work in a way that was both persuasive and funny).

The last slide of Darren's talk; original source unknown

But perhaps the talk I enjoyed most was Vanessa’s on neck support hypotheses (ligament, pneumatic stabilisation, ventral compressing bracing, muscle). It’s only the second time she’s presented at a conference, and the first time ever in palaeo. Having workshopped the content of the talk extensively, first with Matt, then with both of us, she then prepared the presentation within an inch of its life and did a fine job of delivering it.

Me commenting on one of Vanessa's slides. Needless to say, my comments were all helpful, constructive, and tactfully delivered.

There is good news for the 6,999,999,940 of you who missed this conference: the sessions were all recorded on video, and will hopefully become available shortly. And there will be a proceedings volume — exact venue to be announced, but we have some good options. Matt, Vanessa and I will all contribute to this. (Darren won’t, of course, since his talk was describing already-published research.)

And more good news for the future: although the funding for DFG Research Unit 533 is coming towards an end — it has about a year left to run — the people who have been running it are keen to hold a 3rd International Workshop, in maybe three years’ time. It’s not clear yet where the funding will come from, but let’s hope they come up with something!

… and a correction to Taylor et al. (2009)

One point that came up in Kent Stevens’ talk was a factual correction to something we wrote in our 2009 neck-posture paper, and it seems right that we should put it on the record. We wrote (Taylor et al. 2009:216) that:

Physical manipulation of the mounted Diplodocus skeleton DMNH 1494, by Ken Carpenter, resulted in a mounted posture in which the neck is extended farther vertically and horizontally than is allowed by Stevens and Parrish’s digital model (personal observation). Since the neck of this mount is a cast of the Diplodocus carnegii holotype CM 84, the very same individual used by Stevens and Parrish (1999), it is evident that the results of such computerised studies are not as objective as they may appear.

The Denver Diplodocus mount

Regarding the provenance of the Denver Diplodocus mount, we were misled by the DMNH online catalogue. Sadly, it doesn’t seem to be online any more, but this is the information it gave regarding the reconstructed portions:

Kent has spoken to Ken Carpenter about this mount, and it turns out that while the majority of the neck is indeed a CM 84 cast, the last three or so posterior cervicals are from a different specimen — presumably DMNH 1494 itself — and are somewhat restored in plaster. Thanks to Kent for clearing this up.

Update (the next day)

Thanks for John H. and Heinrich, who both tweeted the conference. You can (for now, anyway) read their comments, and a few by other people, in the saved messages under #SauroBonn. But I don’t know how long they last, and I don’t know a good way to save them. Can anyone help?

October 20, 2009

At the 2007 SVP meeting in Austin, Texas, I noticed that the suffix “-ass” was ubiquitiously used as a modifier: where an Englishman such as myself might say “This beer is very expensive”, a Texan would say “That is one expensive-ass beer” — and the disease seemed to spread by osmosis through the delegates, so that by my last day in Austin is was seemingly impossible to hear an adjective without the “-ass” suffix.

All of which is by way of introducing the fact that Futalognkosaurus really was a big-ass sauropod, as this photo of its sacrum (with articulated ilia) shows:

A version of this photograph (in black and white and with the background chopped out) appeared in Ferdinand Novas’s recent book (Novas 2009) and attracted some discussion on the Dinosaur Mailing List.

Although in the past, we have complained about the lack of measurements in the two papers describing Futulognkosaurus (Calvo et al. 2007, 2008), this photo demonstrates a lower bound on its size: we know that it was, at least, Darned Big. (I would attempt to calculate some measurements from this photo using Porfiri as my scale-bar, but we all know how variable human proportions are, so it’s probably better to refrain.) The great news here is that, as explained by Ruben Juarez Valieri in a comment on an earlier article, a third article is on the way that will contain all the measurements we want.

Anyway, here are some more of Calvo’s awesome Futalognkosaurus photos, all used with grateful permission:

Articulated dorsal vertebrae of Futalognkosaurus in ?ventral view. And there is Juan Porfiri again, still 175 cm tall. Photo by kind permission of Jorge Calvo.

How on Earth did they get that jacket out the ground and back to the museum?!

And finally — if you’ll forgive the flagrant appendicularity:

Right ischium and pubis of Futalognkosaurus in ventrolateral view. Where's Juan? Photo by kind permission of Jorge Calvo.

And now for something completely different:

Open Access Week

I’m pleased to say that this week (October 19-23) is Open Access Week. Get over to the site for statistics about the rise of open access. Particularly impressive is a sequence of institutions that are introducing open-access mandates, i.e. requiring that all research produced by its staff is made freely available to the world. We’re on the way!

October 13, 2009

UPDATE December 3, 2009

I screwed up, seriously. Tony Thulborn writes in a comment below to correct several gross errors I made in the original post. He’s right on every count. I have no defense, and I am terribly sorry, both to Tony and to everyone who ever has or ever will read this post.

He is correct that the paper in question (Thulborn et al 1994) does discuss track length, not diameter, so my ranting about that below is not just immoderate, it’s completely undeserved. I don’t know what I was thinking. I did reread the paper before I wrote the post, but I got the two switched in my mind, and I assigned blame where none existed. In particular, it was grossly unfair of me to tar Tony’s careful work with the same brush I used to lament the confused hodgepodge of measurements reported in the media (not by scientists) for the Plagne tracks.

I am also sorry that I criticized the 1994 paper and implied that the work was incomplete. I was way out of line.

I regard this post as the most serious mistake in my professional career. I want very badly to somehow unmake it. I am adding corrections to the post below and striking out but not erasing my mistakes; they will stand as a reminder of my fallibility and a warning against being so high-handed and unfair in the future.

I’m sorry. I beg forgiveness from Tony, from all of our readers, and from the broader vertebrate paleontology community. Please forgive me.

–Mathew Wedel

You might have seen a story last week about some huge sauropod tracks discovered in Upper Jurassic deposits from the Jura plateau in France, near the town of Plagne. According to the news reports, the tracks are the largest ever discovered. Well, let’s see.

The Guardian (from which I stole the image above) says the prints are “up to 2 metres (6ft 6 in) in diameter”, but ScienceDaily says “up to 1.5 m in total diameter”. Not sure how ‘total diameter’ is different from regular diameter, but that’s science reporting for you. The BBC clarifies that, “the depressions are about 1.5m (4.9ft) wide”, which might be the key here (see below), but then mysteriously continues, “corresponding to animals that were more than 25m long and weighed about 30 tonnes.” I find it rather unlikely that a pes track 1.5 m wide indicates an animal only as big as Giraffatitan (hence this post).

So there’s some uncertainty with respect to the diameter of the tracks–half a meter of uncertainty, to be precise. But sauropod pes tracks are usually longer than wide, and a print 1.5 m wide might actually be 2 m long.

Not incidentally, Thulborn (1994) described some big sauropod tracks from the Broome Sandstone in Australia, with pes prints up to 1.5 m. Although the photos of the tracks are not as clear as one might wish, they do appear to show digit impressions and are probably not underprints. [See Tony Thulborn’s comment below regarding footprints vs underprints.]

I’ll feel a lot better about the Plagne tracks when the confusion about their dimensions is cleared up and when some evidence is presented that they also are not underprints. In any case, the only dimension with any orientation cited for the Plagne tracks is the 1.5 m width reported by the BBC, so we’ll go with that. So the Plagne tracks might only tie, but not beat, Thulborn’s tracks.

…Then again, Thulborn only said that the biggest tracks were up to 150 cm in diameter. What does that mean–length? Width? Are the tracks perfect circles? Does no one who works on giant sauropod tracks know how to report measurements? These questions will have to wait, because despite the passing of a decade and a half, the world’s (possibly second-) biggest footprints–from anything! ever!–have not yet merited a follow-up paper.[Absolutely wrong and unfair; please see the apology at top and Tony Thulborn’s comment below.]

Nevertheless, for the remainder of this post we’ll accept that at least some sauropods were leaving pes prints a meter and a half wide. Naturally, it occurs to me to wonder how big those sauropods were. I don’t know of any studies that attempt to rigorously estimate the size of a sauropod from its tracks or vice versa, so in the finest tradition of the internet in general and blogging in particular, I’m going to wing it.

How Big?

First we need some actual measurements of sauropod feet. When Mike and I were in Berlin last fall (gosh, almost a year ago!), we measured the feet (pedes) of the mounted Giraffatitan and Diplodocus for this very purpose. The Diplodocus feet were both 59 cm wide, and the Giraffatitan feet were 68 and 73 cm wide. The Diplodocus feet are trustworthy, the Giraffatitan bits less so. Unfortunately, the pes is the second part of the skeleton of Giraffatitan that is less well known than I would like (after the cervico-dorsal neural spines). The reconstructed feet look believable, but “believability” is hard to calibrate and probably a poor predictor of reality when working with sauropods.

One thing I won’t go into is that Giraffatitan (HM SII) probably massed more than twice what Diplodocus (CM 84/94) did, but on the other hand G. bore more of its weight on its forelimbs. It would be interesting to calculate whether the shifted center of mass would be enough to even out the pressure exerted by the hindfeet of the two animals; Don Henderson may have done this already.

Anyway, let’s say for the sake of argument that the hindfeet of the mounted Giraffatitan are sized about right. The next problem is figuring out how much soft tissue surrounded the bones. In other words, how much wider was the fleshy foot–deformed under load!–than the articulated pes skeleton? I am of two minds on this. On one hand, sauropods probaby had a big heel pad like that of elephants, and it seems reasonable that the heel pad plus the normal skin, fat, and muscle might have expanded the fleshy foot considerably beyond the edges of the bones. On the other hand, the pedal skeleton is widest across the distal ends of the phalanges, and in well-preserved tracks like the one below the fleshy foot is clearly not much wider than that (thanks, Brian, for the photo!).

Bear in mind that a liberal estimate of soft tissue will give a conservative estimate of the animal’s size, and vice versa. Looking at the AMNH track pictured above, it seems that the width added by soft tissue could possibly be as little as 5% of the width of the pes skeleton. Skewing hard in the opposite direction, an additional 20% or more does not seem unreasonable for other animals (keep in mind this would only be 10% on either side of the foot). Using those numbers, Diplodocus (CM 84/94) would have left tracks as narrow as 62 cm or as wide as 71 cm. For Giraffatitan (HM SII) I’ll use the wider of the two pes measurements, because the foot is expected to deform under load and the 73 cm wide foot looked just as believable as the 68 cm foot (for whatever that’s worth). Applying the same scale factors (1.05 and 1.20) yields a pes track width of 77-88 cm.

These numbers are like pieces of legislation, or sausages: the results are more pleasant to contemplate than the process that produced them. They’re ugly, and possibly wrong. But they give us someplace to start from in considering the possible sizes of the biggest sauropod trackmakers. Something with a hindfoot track 1.5 meters wide would be, using these numbers, conservatively more than twice as big as (2.11x) the mounted Carnegie Diplodocus or 170% the size of the mounted Berlin Giraffatitan. That’s right into Amphicoeliasfragillimus/Bruhathkayosaurus territory. The diplo-Diplodocus would have been 150 feet long, and even assuming a very conservative 10 tons for Vanilla Dippy (14,000L x 0.7 kg/L = 9800 kg), would have had a mass of 94 metric tons (104 short tons). The monster Giraffatitan-like critter would have been “only” 130 feet long, but with a 14.5 meter neck and a mass of 113 metric tons (125 short tons; starting from a conservative 23 metric tons for HM SII).

Keep in mind that these are conservative estimates, for both the size of the trackmakers and the masses of the “known” critters. If we use the conservative soft tissue/liberal animal size numbers, the makers of the 1.5 meter tracks were 2.4 times as big as the mounted Diplodocus or almost twice as big as the mounted Giraffatitan, in which case masses in the blue whale range of 150-200 tons become not just probable but inevitable.

Mike measuring Giraffatitan's naughty bits. Check out the hindfeet. Also note the sauropod vertebrae in the background--titular obligation fulfilled!

Too Big?

Going the other way, I can think of only a handful of ways that the “conservative” trackmaker estimates might still be too big:

First, the pes of Giraffatitan might have been bigger than reconstructed in the mounted skeleton. Looking at the photo above, I can image a pes 10% wider that wouldn’t do any violence to the “believability” of the mount. That would make the estimated track of HM SII 10% wider and the estimated size of the HM-SII-on-steroids correspondingly smaller. But that wouldn’t affect the scaled up Diplodocus estimate, and the feet of Giraffatitan would have to be a LOT bigger than reconstructed to avoid the reality of an animal at least half again as big as HM SII.

Second, the amount of soft tissue might have been greater than even the liberal soft tissue/conservative size estimate allows. But I think that piling on 20% more soft tissue than bone is already beyond what most well-preserved tracks would justify, so I’m not worried on that score. (What scares me more is the thought that the conservative estimates are too conservative, and the real trackmakers even bigger.)

Third, I suppose it is possible that sauropod feet scaled allometrically with size and that big sauropods left disproportionately big tracks. I’m also not worried about this. For one thing, when they’ve been measured sauropod appendicular elements tend to scale isometrically, and it would be weird if feet were the undiscovered exception. For another, the allometric oversizing of the feet would have to be pronounced to make much of a dent in the estimated size of the trackmakers. I find the idea of 100-ton sauropods more palatable than the idea of 70-ton sauropods with clown shoes.

Fourth, the meta-point, what if the Broome and Plagne tracks are underprints? [Please see Tony Thulborn’s comment below regarding footprints and underprints.] I’ve seen some tracks-with-undertracks where the magnification of the apparent track size in the undertracks was just staggering. The Broom tracks have gotten one brief note and The Plagne tracks have not been formally described at all, so all of this noodling around about trackmaker size could go right out the window. Mind you, I don’t have any evidence that the either set are underprints, and at least for the Broome tracks the evidence seems to go the other way, I’m just trying to cover all possible bases.

Conclusions

So. Sauropods got big. As usual, we can’t tell exactly how big. Any one individual can leave many tracks but only one skeleton, so we might expect the track record to sample the gigapods more effectively than the skeletal record. Interestingly, the largest fragmentary skeletal remains (i.e., Amphicoelias and Bruhathkayosaurus, assuming they’re legit) and the largest tracks (i.e., Plagne and Broome) point to animals of roughly the same size.

It’s also weird that some of the biggest contenders in both categories have been so little published. I mean, if I had access to Bruhathkayosaurus or a track 1.5 m wide, you can bet that I’d be dropping everything else like a bad habit until I had the gigapod evidence properly written up. What gives?[The implication that the Broome tracks were not properly written up is both wrong and unfair; please see the apology at top.]

Finally, IF the biggest fragmentary gigapods and the biggest tracks are faithful indicators of body size, they suggest that gigapods were broadly distributed in space and time (and probably phylogeny). I wonder if these were representatives of giga-taxa, or just extremely large individuals of otherwise vanilla sauropods. Your thoughts are welcome.

Epilogue: What About Breviparopus?

It’s past time someone set the record straight about damn Breviparopus. The oft-quoted track length of 115 cm is (A) much smaller than either the Broome or Plagne tracks, and (B) the combined length of the manus and pes prints together; I know, I looked it up (Dutuit and Ouazzou 1980). Why anyone would report track “length” that way is beyond me, but what is more mysterious is why anyone was taken in by it, since the width of 50 cm (pathetic!) is usually quoted along with the 115 cm “length”, indicating an animal smaller than Vanilla Diplodocus (track length is much more likely than width to get distorted by foot motions during locomotion) [This part is wrong; see the update below.]. But people keep stumbling on crap (thanks, Guiness book!) about how at 157 feet long (determined how, exactly?) Breviparopus was possibly the largest critter to walk the planet. Puh-leeze. If there’s one fact that everyone ought to know about Breviparopus, it’s that it was smaller than the big mounted sauropods at museums worldwide. The only thing super-sized about it is the cloud of ignorance, confusion, and hype that clings to the name like cheap perfume. Here’s the Wikipedia article if you want to do some much-needed revising.

UPDATE (Nov 17 2009): The width of the Breviparopus pes tracks is 90 cm, not 50 cm. The story of the 50 cm number is typically convoluted. Many thanks to Nima Sassani for doing the detective work. Rather than steal his thunder, I’ll point you to his explanation here. Point A above is still valid: Breviparopus was dinky compared to the Broome and Plagne trackmakers.

Parting Shot

You know I ain’t gonna raise the specter of a beast 1.7 times the size of HM SII without throwing in a photoshopped giant cervical. So here you go: me with C8 of Giraffatitan blown up to 170% (the vert, not me). Compare to unmodified original here.

April 23, 2009

Here's your new t-shirt/sticker/desktop wallpaper. Tell the world.

OMG! WTF? Was I asleep? Had I slept? Did I miss something? Does paleontological training destroy the part of the brain that knows how to use a freakin’ tape measure? Are paleontologists incapable of imagining that others might want to make meaningful comparisons with their taxa? Has phylotardation reached the point where people think the character taxon matrix contains all relevant information? Somebody throw me a bone here–so I can measure the damn thing!

Way back when, I discussed the question, “How big was Futalognkosaurus?”, which at the time had only been described in one fairly brief publication (Calvo et al. 2007). Nothing wrong with that, lots of dinos get described that way, and little damage is done to science as long as the follow-up descriptions do eventually appear (sometimes they don’t). But Calvo et al. (2008) put out a longer description of Futalognkosaurus the very next year, for which they are to be commended.

It’s not all roses, though. You’ll recall that one of the problems with the original paper was that it didn’t include many measurements, and the scale bars in the photographs and the skeletal reconstruction disagreed wildly. I was hoping that Calvo et al. (2008) would include a table of measurements; actual measurements of one of the most complete large titanosaurs would be invaluable for those of us who are interested in body proportions, neck elongation, mass estimation, and all that good stuff. But sadly the second paper contains no table and almost no measurements; again, it’s all done with scale bars, and since many of the figures appear to be identical to those from the first paper, the precision of the scale bars is hard to determine but possibly low.

It blows my damn mind that a century ago people like Charles Whitney Gilmore and John Bell Hatcher could measure a dinosaur to within an inch of its life, and publish all of those measurements in their descriptions, and lots of folks did this and it was just part of being a competent scientist and doing your damn job. And here we are in the 21st century with CT machines, laser surface scanners, ion reflux pronabulators and the like, and using a narf-blappin’ TAPE MEASURE is apparently a lost art. This vast inexplicable deficiency is not limited to any one working group or country or continent or language, either. Nigersaurus is known from multiple specimens and has been the subject of three separate peer-reviewed papers spread out over a friggin’ decade, but good luck trying to figure out the dimensions of the individual bones.

Dammit, people! Tape measures. Tables of measurements. These are dead simple, cost almost nothing, and add measurably to the usefulness* of descriptive work.

* as in citeability, which none of us can afford to ignore

From now on, when people describe sauropods and don’t publish any measurements, said omissions will be trumpeted here and the perpetrators will be savagely mocked.

You’ve been warned.

Disclaimer

With so many offenders, it’s a bit unfair to single out Calvo et al. for scorn. I am glad that they provided a longer description, which is more than I can say for many. And I have to give them mad props because both Futalognkosaurus papers are freely available at Proyecto Dino. But someone had to get the Wonka ticket in the MYDD! lottery, and they won because I’d been so looking forward to the follow-up paper so that I could answer the original question. Someone with a tape measure and a plane ticket to Argentina (or Beijing, or Chicago) could do a crapload of useful science. Sheesh!